How do I determine transmission slip and identify leak?

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I am fairly certain my transmission is slipping... spent a week at auto shop, who said 'nothing is wrong with the transmission'. Had a shredded belt replaced & an interior air filter. Mechanics said that I have a wheel-bearing on back left that is going to need to be replaced and that was all... I had asked for a computer diagnostics to be run, I would think something related to the transmission might would show up indicating a problem(?) - I do not know if they actually performed the test or not. But course, the jerking motion has gotten worse to the point that I was unsure if the care was about to die or not. Also, the engine revs up to 3 when accelerating from 0 up to ~ 30mph. Feels like changing gears is an issue (like they are getting stuck?). I do not know... I know very little about cars but I DO know that whatever this is, has something with the transmission. The engine light just came on, all interior/dashboard lighting disappeared, then the check engine light appeared, followed by all of the other (on dash). I was 2-3 miles from home. Parked it only to see it is leaking some kind of fluid now, toward the front, right side, can't figure out what it is (it's not red, pink, brown or black and it's not water). Anyone that read this, feel free to post any advice - Thanks in advance.